Black Oystercatchers nest on restored shoreline

Black Oystercatchers nest on Aramburu Island!

JULY 2018 UPDATE: We are currently monitoring the Black Oystercatchers! The pair has returned to Aramburu and has established a nest behind one of the eucalyptus logs that was installed to prevent shoreline erosion.  Both the male and female are taking turns incubating the eggs. It is difficult to see the nest, but we suspect that there are 2-3 eggs! The eggs were laid around May 31st, so we suspect they will hatch around June 28th. Stay tuned!

JULY 2017 UPDATE:  We monitored the Black Oystercatcher pair all season from May through July. The pair returned to Aramburu and appeared to nest build but we never found a nest or eggs on the island. Recently, there have been high numbers of ravens and crows on the island, so it's possible that a nest was depredated. 


Black Oystercatcher family on Aramburu Island, June 2016. Photo: K. Wilcox

Each year since restoring Aramburu Island, Black Oystercatchers return to nest on the enhanced beach. 

Black Oystercatchers can lay 1-3 eggs, but two is more common, and previous clutches of what is assumed to be the same pair on Aramburu have been limited to two.  In 2016, all three eggs hatched on or about June 21st, and three hatchlings were seen stumbling about the nest area soon after.  On July 19, 2016, only two of the three chicks were seen, but both were eating well and looking healthy.  At about five weeks the chicks fledged. 

2016 marks the fourth year oystercatchers nested on the island after the shoreline enhancement was completed. 


The Black Oystercather pair has successfully nested again on Aramburu Island in 2015. In mid-June, a pair of eggs hatched and two chicks were seen on the beach not far from where they had nested in 2014. About two-weeks later, the pair was down to just one, but at the time of this writing the remaining chick is about 3 and 1/2 weeks old and looks strong and healthy. Both parents are still attending to it with large food, but the chick is regularly seen foraging in the surf. Oystercatcher chicks fledge at about 5 weeks, so we will are looking forward to that next milestone.


On May 29, Richardson Bay Audubon Center & Sanctuary (RBACS) volunteers conducting a shorebird survey observed a Black Oystercatcher that appeared to be sitting on a nest on Aramburu Island (property of Marin County Parks) in Richardson Bay.  Subsequent inspections by Audubon staff confirmed there were two eggs in the scrape. The location of this nest was on the newly constructed shoreline habitat of Aramburu Island, a location specifically designed as part of the Aramburu Island Enhancement Project to attract shorebirds such as the oystercatchers.

On June 23, an RBACS volunteer noticed at least one hatchling, and the second chick was soon confirmed.

Both chicks were well cared for by the attentive parents. By that Friday the oystercatchers had moved away from the nest site and were all seen foraging on the beach.  At some point during the first two weeks, one of the chicks appeared to have been lost.  Fortunately, the other chick continues to grow and thrive as of this writing, gaining weight, exercising its wings and learning to forage on its own.

This development complements Audubon’s statewide effort to understand and conserve Black Oystercatcher, which is considered highly vulnerable to climate change. Starting in 2011, the Audubon network and many state and federal agency partners have completed population and productivity surveys, filling a major gap in understanding of the species in the state. Audubon chapters and agency partners have conducted conservation activities aimed at reducing disturbance and enhancing public awareness of black oystercatchers.

Black Oystercatcher (Haematopus bachmani) has been identified as a Focal Species by the U.S. Fish & Wildlife Service due to its rarity and vulnerability to a number of threats. It is also one of Audubon California's birds of concern.

This news represents a major success for the Aramburu Island Enhancement Project, not only because it confirms the value of the new shoreline design for erosion control and shorebird habitat, but also because Aramburu Island becomes one of only four known nesting sites for Black Oystercatchers within the San Francisco Bay. This also highlights the importance of undisturbed shoreline habitat within the Bay in general.

Aramburu Island is a great example of a habitat enhancement project that provides valuable ecosystem services for humans as well as wildlife. A former dumpsite, the Island now supports a wide variety of shorebirds and waterfowl. Additionally, the new shoreline, along with the creation of a suite of new wetlands, has resolved a serious erosion issue on the island and now provides improved sea-level rise and flood resiliency to the Strawberry shoreline.  Audubon will continue to monitor the success of the enhancement features, both for birds and for people, through 2021.

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